<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>1姓名案例-computed实现</title>
        <!-- 引入Vue -->
        <script type="text/javascript" src="../js/vue.js"></script>
    </head>
    <body>
        <!-- 准备好一个容器-->
        <div id="demo">
            姓：<input type="text" v-model="firstName"> <br>
			名：<input type="text" v-model="lastName"> <br>
			全名：<span>{{fullName}}</span>
        </div>
    </body>

    <script type="text/javascript">
        //阻止 vue 在启动时生成生产提示。
        Vue.config.productionTip = false
        new Vue({
			el:'#demo',
			data:{
				firstName:'zhang',
				lastName:'san',
                fullName:''
			},
            // 异步任务用watch可以实现,computed不能
			watch: {               
				firstName(val){
					this.fullName =val+ '-' + this.lastName
				},
                lastName:{
                    immediate:true,
                    handler(val){
                       setTimeout(()=>{
                        this.fullName =this.firstName+ '-' + val
                       },1000)
                    
                }
            }
			}
		})
    </script>
</html>